Albert Abraham Michelson

Michelson, Albert Abraham (mĪˈkəlsən) [key], 1852–1931, American physicist, b. Strelno, Prussia, grad. Annapolis, 1873, and studied at Berlin, Heidelberg, and Paris. He was professor of physics at Clark Univ. (1889–92) and later was head of the department of physics at the Univ. of Chicago (1892–1931). He is known especially for his determinations of the speed of light; in some of his earliest work he tested the data of Foucault's experiments and, then and later, with apparatus (including the interferometer) that he designed and built himself, measured the speed of light to an unequaled degree of accuracy. He measured (1892–93) the length of the standard meter in Paris in terms of the wave length of the red line of the cadmium spectrum, using his interferometer method. The wave length thus provided an absolute and exactly reproducible standard of length. With E. W. Morley he conducted the Michelson-Morley experiment (1887), which failed to detect any difference in the speed of light caused by the motion of the earth through space. That led to the refutation of the ether hypothesis and contributed to the development of Einstein's theory of relativity. Michelson was the first to measure the diameter of a distant star. He also demonstrated that the earth as a whole is rigid, not molten. Awarded the 1907 Nobel Prize in Physics, he was the first American scientist to receive the honor. His major writings include Velocity of Light (1902) and Studies in Optics (1927).